Question: In 1939, what country did Marlene Dietrich become a citizen of?
Paraphrase: Which country became a citizen of Marlene Dietrich in 1939?
SPARQL (Wikidata): SELECT ?obj WHERE { wd:Q4612 p:P27 ?s . ?s ps:P27 ?obj . ?s pq:P580 ?x filter(contains(YEAR(?x),'1939')) }